Method of producing multiply metalfoil-cardboard material and of producing articles formed of such material



June 30, 1953 F. P. LENARD ET AL 2,643,593 METHOD OF PRODUCING MULTIPLY METAL-FOIL-CARDBOARD MATERIAL AND OF PRODUCING ARTICLES FORMED OF SUCH MATERIAL Filed Oct. 30, 1948 2 Sheets-Sheet l o a if-41 I w I l 10 g 19 7 2'6 3 9 2 5% a e m 6m 2 w in mu DE m OM B DH mo L AR 0 nm B o R A m C L m PM G F N NI c CU UD D0 0R RP. P F m 3D 5m 9T 0.. 11 3 9M 0 L 3 m e d m .w J m Patented June 30, 1953 MATERIAL AND- OF PRODUCING. ARTICLES FORMED OF; SUCH FQIIu-GA-RDBOARD MATERIAL Frederick Pyne= Lenard and Geofirey William Methven, London; England, assignors to The NewiMerton- BoardMills Limited, London England a company'oi' Great Britain and Northern Y Ireland Aipplica-ti'on ctob'er30, 1948, Serial No. 57,524 In Great Britain November 5, 1947 Claims; (01. assed) The. present; invention. relates-1 to articles. made of: a. plurality of plies; of cardboardzor paper or the like. (hereinafter referred to as. cardboard) adhesively bonded together and methods: of making such articles. As the dividing. line, ifany, between cardboard; and. paper isindefinabl'e, and: as; the terms cardboard anck-pap.er;."here.-. tofore,. have. commonly been. used; interchange..-

ably, the term cardboard has been employed in.

a broad. sense. in the present. specification. and in the accompanying claims, to; refer-to either cardeboardor paper...

It. known that. metal: foil: can be: bonded. t

cardboard by an adhesive of the thermoi-settingi type such. as a. starch. paste-urea. formaldehyde resin so; as to withstand .the direct contact. of;

steam: without peeling off. Since; the. machines;

for lining cardboard and the like. with metal. foil:

are very delicate owing; to the extreme thinness of the: foil.used,. it. is. not possible touse an.ad-

hesivewhich cannot always. be redissolved; in.- a.

solvent, since such adhesive. cannotreadily be. cleaned ofi the machines. after; use.f. It: is, in:- fact, necessary to use; anadhesive which is. al;

ways liquid. soluble so. that: the: lining. machines; The starch,

may be. cleaned down after: use.. paste-urea formaldehyde. adhesive above. men, tioned has commonly mixed: withr'it; a. little ammonium chlorideas a hardening. agent, so that.

ithardens at: room. temperature; in 2-3. days and;

in thin. layers, in a: considerably shorter" time,.

thus: making. itcompletely: unsuitable for this purpose.

Itais' an object of the present invention to. pro

duce articles. of. multi-ply cardboard. and foil which can: be brought: into direct. contact with. steamwithout peelingv of: the foil.

According to the presentzinvention. a method-f: making multi-ply' metal" foil. cardboard. material comprises forming a composite web of: cardboard:

and metal foil adhesively joinedfby means of a.

liquid soluble adhesive, said. liquid. soluble adihesive being convertible to a water insolublecomplex by treatment. with. formaldehyde, bonding two onmorei layers of the composite web' together by: means of: a thermo-setting adhesive contain Alternatively the material may be 2. cardboard. together may conveniently be a: caseinadhesive' and the second. adhesive may be a thermo-set-ting: adhesive: containing; urea-formaldehyde. Onzthe application of heat, formaldehyde permeates the cardboard and condenses with; the: casein to form: a. thermo-setting substance.

In the composite web above. referred to; a single web of: metal. foil. only may be used, but two webs of: cardboard: may; be. employed, bothsurfaces-of. the-metalfoilibeingi adhered to cardboard.

It is..known to construct acontainer having a. cylindrical bodyofseyeralplies of: cardboard ad.-' hesively bonded: together; and a container of. considerable strength; may be; formed? in; this way, whichv still has walls of considerable flexibility.

It is anobjectuof the present invention to pro.- vide: a .containerof; multi-ply cardboard oonstruction. for thevacuumpackinaof food which may. be of alarger; size. than the tin can normally usedfor this: purpose.

In. the; normal systemof vacuum packing of food the. cans arezfilledz and; sealed; and: are then heated to G; forsterilisatiom in.- apressure cooker in which. are exterior pressure, may be appliedto:the.: cans. greater than the; pressure inside. thezcan; generated by heating. on cooling, aconsiderable: vacuum occurs inside; the. can and if: the: canals. of: large size; such as would be, re-

quiredlfora capacity-of 56 lbs.,.there. is atendency' to collapse, unless the can is made of heavier gauge metalthanzuscd for'the normal- 1; 1b. cans. The-:use of arheavy gaugemetal introduces; many complications: and ithas not: been. practicable to usea can of? large; capacity;

A. drum, according to: afuhther feature of the invention, comprises; a. convolutely wound cylindrical; body: portion: and separately: formed metal ends pieces.- engaging; the: ends. of: said body. portion, said. convolutely; wound body portion com-- prising a. plurality of layers: of: metal foil and cardboard adhesively' bonded: together: bymeans of a water insoluble adhesive. The: end' nieces will preierab'lybe formed. of: a. metal such as alu-miniumi which: is 1 relatively; inert; to" food acids, the" top end piece. being: formed with: a vacuum closure: of any convenient: design.

The invention is illustratedi with. reference to the accompanying drawings wherein:

Fig; 1' shows an elevatiomofradrum partly in; section.

Fig. 2 shows a sectional detail of the vacuum; I

Fig. 4 shows an enlarged section detail of the wall of a drum.

Fig. shows a board made in accordance with an alternative form of the present invention.

One application of the present invention is for the production of a 56 lb. container for vacuum packing of fruit pulp or similar substances and is illustrated with reference to Figs. 1-4.

A continuous web of cardboard of .016 inch thickness is lined in a lining machine with aluminium foil of .0005 inch thickness,rthe cardboard and the aluminium being caused to adhere together by means of a liquid soluble casein adhesive. If the composite web at this stage is brought into direct contact with steam or hot water, the aluminium foil quickly peels off from the cardboard.

The composite web in roll form is then transferred to a coiling machine having a collapsible motor-driven rotatable mandrel. The composite web is fed from the roll over a heated roller and is then brought into contact with an adhesive transfer roller, which applies a coating of adhesive to the cardboard side of the composite web and then on to the rotatable mandrel.

One turn of the composite web with the aluminium foil on the inside is made round the mandrel which is turned by hand for this operation. The web is then cut off so as to leave a small overlap, so disposed that when the free end of the composite web roll, foil-side outward, is adhesively attached to the overlapping portion, the web runs in the same direction as before, so that on starting the mandrel drive, the tension of the web tightens the first turn of composite material on to the mandrel.

The machine is so arranged that the web is maintained under tension by means of a brake mechanism on the web spool, in order to keep each turn of the web tight on the mandrel. It is also provided with an automatic cut-oil. on the mandrel drive so that after a predetermined number of rotations the motor stops automatically. The web is then severed. In the present example, ten turns of composite web are used to form the cylindrical coils.

The paste used in conjunction with the coiling machine is composed in the proportion of 30 lbs. starch-flour paste made up with 30 lbs. of water and 28 lbs. urea-formaldehyde, to which ammonium chloride is added as a hardening agent.

The cylindrical coil is removed from the coiling machine and is then stood on end for 5-10 minutes, during which time it becomes sufficiently stiff to handle. The cylinders are then transferred to a trimming machine, in which the edges are out back, since there is a certain amount of wandering in the coiling machine, and the cylinder is divided centrally to provide two bodies for the complete container. From this it follows that the original web must be rather Wider than twice the height of the body of the finished container.

The cylindrical bodies I are removed from the trimming machine and are then stood for -30 minutes over infra-red lamps to set and dry the paste, the bodies i being roughly closed by placing a sheet of asbestos over the top. Temperature measurements taken during the drying showed a temperature of 104 C. at the top of the drum and of 88 C. at the bottom of the drum.

During this drying there is a considerable evolution of formaldehyde from the adhesive and zip ideas 4 this passes through the cardboard and reacts with the casein adhesive used to join the foil to the cardboard to form a new adhesive which is capable of withstanding direct contact with steam.

After removal from the infra-red lamps the vertical seams on the cylinder are sealed by applying a strip 2 of .001 inch aluminium foil of a width of about one inch on the outside and a similar strip 3 on the inside (see Fig. 4); the foil is affixed by the application of a heat-sealing nitrocellulose adhesive, which is then set by applying a hot iron along the seams.

' The body I is then passed to a machine, in which a separately formed aluminium alloy bottom end piece 5 is pressed on, the end piece being formed with a deep annular recess 6 adapted to receive the edge of the cylindrical body i.

The inside of the assembly is then sprayed with nitro-cellulose clear lacquer.

A separately formed top end piece 9, of which the inside has already been sprayed with lacquer, is then pressed onto the cylindrical body, which engages with an annular recess ID in the top end piece.

The body I is then sprayed on the outside with cellulose lacquer and is then stood over an infrared lamp, bottom up, for 15-20 minutes to dry the lacquer.

The purpose of the lacquer spraying is to keep the food acids of the contents of the container away from the metal, since, though the metal is relatively inert to food acids, there may be some corrosion.

After removal from the lamps the walls of the annular recesses 6 and 10 of the top and bottom end pieces are drilled and the two end pieces are attached to the cylindrical body I by hollow rivets I4 at each end.

The top end piece 9 is formed from a single aluminium alloy pressing. In addition to the annular recess formed near the periphery,.the end piece is formed with an opening for filling, adapted to be closed by a vacuum seal. Around the opening is provided a multiple threaded vertical portion l6 and an overhanging annular horizontal portion l1, adapted to be engaged by a similar annular horizontal portion on a dished sealing cover 19, a suitable sealing washer 20 being placed between the two. The closure is completed by a locking cover 22, provided with a peripheral flange formed with multiple threads adapted to engage the threads on the vertical portion 17. The locking cover 22 is provided with a handle 24 for lifting purposes and the said handle is provided with a projecting portion 25 which extends nearly to the edge of the container. The projecting portion is formed with a small aperture 26, through which a wire may be passed and through an adjacent hollow rivet 14 to form a seal against accidental opening of the container.

The dimensions of the completed drum of 56 lbs. capacity is 10 diameter x 17" length.

It should be noted that other water soluble glues may be used to replace casein adhesives, since casein is not the only water soluble substance used in adhesives to be rendered insoluble by formaldehyde. For instance it is well known that gelatinous glues can be hardened by formaldehyde.

To give one example of a vacuum packing process to which the container so constructed can be used, a container was filledv with fruit pulp at a temperature of C.- C. It was then closed by ineans of the sealing cover I9 and the. lockin cover 22 was screwed down. The filled container was then placed in a pressure cooker and heated to. 120 C; to sterilise the fruit pulp,. the pressure on the outside of the container being maintained.

slightly greater than the pressure; on the inside,- exerted by the hot contents. 4 After about 35 minutes coldwaterwasisprayed on to the container and after an initial cooling? before being discarded'and has a definite advantage over the normal can, which may only be used once.

By use of the present invention a. composite, board may be produced which has goo'dwater resisting and insulating properties. Two composite we s of cardboard and aluminium foil, produced as in the'previous instance, are bonded together with their cardboardsurfaces inwards in-alaminating machine by means of starch paste-urea formaldehyde adhesive applied: to the cardboard surface of one of the webs, andthe laminated board'is cut off into lengthsand stackedi. It is not heat treated, but, instead; is left for about .14 da s, in which time the urea formaldehyde adhesive has setand sufiicient. gaseous formaldehyde has permeated. the cardboard to set the casein adhesivev and render-iii water insoluble.

The board produced by this means is shown in Fig. 5, in which the aluminium foil plies 3! are on the outside and the cardboard plies 3! are between them.

A board thus formed has good heat insulating properties, as the aluminium foil acts as a reflector of radiant heat and the cardboard acts as an insulator for conducted heat. The foil also forms an impermeable layer for the protection of the cardboard, so that a board made in this way may be washed down with water without damage.

What we claim and desire to secure by Letters Patent is;

1. A method of producing multi-ply metalfoilcardboard material comprising first forming a composite web of cardboard permeable by formaldehyde and an impermeable metal foil by adhesively joining the two in face-to-face relationship by means of a liquid soluble adhesive which is convertible to a water insoluble complex by treatment with formaldehyde, then applying precondensed formaldehyde resin adhesive containing uncondensed formaldehyde to the then exposed face of the cardboard, and then subjecting the composite web to temperature conditions for a duration of time dependent upon such temperature; the time being of relatively long duration in the presence of relatively low temperatures such as room temperatures and of relatively shorter duration in the presence of relatively higher temperatures.

2. A method of producing multi-ply metal-foilcardboard material comprising first forming a composite web of cardboard permeable by formaldehyde and an impermeable metal foil by adhesively joining the cardboard and the metal foil in face-to-face relationship by means of a water soluble adhesive. which is-convertibl'e. to a water insolu-ble complex by treatment with. formai'dehyde, thenbonding cardboard. and metal foil faces of such composite webtogether by means of 'a precondensed formaldehyde resin adhesive contain.- ing uncondensed formaldehyde and seasoning by storage thelaminatedl material. thus produced to thus convertsaid water soluble adhesive by penetration. of the. formaldehyde through. the cardboard-..

31 A. method. of producing multiI-ply metal-foil cardboard laminae adhesively bonded" together comprising first forming a composite web. of card'- board permeable by f'ormald'ehydeand' an: im' permeable metal foil by adhesively joining the cardboard and" the metal foil in face-t-o-facc relationship by means of a water soluble adhesive including. casein, bonding cardboard and metal foil? faces of such composite; web together by means of a precondense'd formaldehyderesin ad'- hesiv'e containing uncondensed formaldehyde, and heating the laminae to liberate formaldehyde from. said second adhesive'to. set said casein containing. adhesive by penetration of the forma1dehyde through the cardboard and to' harden said formaldehyde resin adhesive.

4. A method of producing multi-ply metal -foi'l cardboard material comprising first forming" two composite webs of cardboard permeable by' formalde'hyd'e' and" an impermeable metal foil by adhesively joining the two cardboard and the metal foilfor each webin fac'e-to f'ace' relationship by means of a water soluble adhesive which is con-- vertibl eto a-water insoluble complex by treatment i with formaldehyde, coating the cardboard surfaceof' at least one of sai d composite webs with a precondensed formaldehyde resin adhesive containing uncondensed fbrmaldehyde, bondingsaid webs'to each other so that thecardboard surfaces of the two composite webs are in intimate faceto-face association and the metal foil surfaces of both of said composite webs face outwardly, and seasoning b-y storage the laminated material thus produced to thus convert said water soluble adhesive by penetration of the formaldehyde through the cardboard.

5. A method of producing multi-ply metal-foilcardboard cylindrical drum bodies comprising first forming a composite Web of cardboard per meable by formaldehyde and an impermeable metal foil by adhesively joining the two in faceto-face relationship by means of a liquid soluble adhesive which is convertible to a water insoluble complex by treatment with formaldehyde, drawing said composite web from a reel, applying a precondensed thermosetting formaldehyde resin containing uncondensed formaldehyde adhesive continuously to at least one side of said composite web, tightly coiling said adhesively coated web into a cylinder, thereby bringing the cardboard and metal foil surfaces of the composite web into intimate face-to-face association with the latter adhesive therebetween and in contact with both such surf-aces, cutting off said web after a predetermined number of turns and heating the cylindrical body so formed to liberate formaldehyde from said second adhesive to thus convert said first adhesive by penetration of the formaldehyde through the cardboard and harden said second adhesive.

6. A method of producing multi-ply metal-foilcardboard containers comprising first forming a composite web of an impermeable metal foil and cardboard permeable by formaldehyde by adhesively joining the two in face-to-face relationship by means of a water soluble adhesive which is convertible to a water insoluble complex by treatment with formaldehyde, coating the cardboard surface of the composite web with a precondensed formaldehyde resin adhesive containing uncondensed formaldehyde, coiling and bonding the web with its metal-foil surface inwardly, severing the web, continuing coiling and bonding the web with the metal-foil surface outwardly on the core so formed, severing the web after a predetermined number of turns, heating the cylindrical body so formed to harden the precondensed formaldehyde resin adhesive and to liberate formaldehyde to thus convert the water' soluble adhesive by penetration of the formaldehyde through the cardboard and applying separate metal pieces to form the end closures of the container.

7. A method of producing multi-ply metal-foilcardboard material comprising first forming a composite web of cardboard permeable by formaldehyde and an impermeable metal foil by adhesively joining the two in face-to-face relationship by means of a liquid soluble adhesive which is convertible to a water insoluble complex by treatment with formaldehyde, then bonding a second piece of cardboard adhesively to the then exposed cardboard face of the composite web by means of a precondensed formaldehyde resin adhesive containing uncondensed formaldehyde, and then subjecting the resulting composite web to temperature conditions for a duration of time dependent upon'such temperature; the time being of relatively long duration in the presence of relatively low temperatures such as room temperatures and of relatively shorter duration in the presence of relatively higher temperatures.

8. A method of producing multi-ply metal-foil cardboard material comprising first similarly forming two separate composite webs of cardboard permeable by formaldehyde and an impermeable metal foil by adhesively joining a sheet of such cardboard and a sheet of such metal foil in face-to-face relationship by means of a liquid soluble adhesive which is convertible to a water insoluble complex by treatment with formaldehyde, then bonding the two composite webs together with their cardboard faces in face-to-face relationship by means of a precondensed formaldehyde resin adhesive containing uncondensed formaldehyde, and then subjecting the joined composite webs to temperature conditions for a duration of time dependent upon such temperature; the time being of relatively long duration in the presence of relatively low temperatures such as room temperatures and of relatively shorter duration in the presence of relatively higher temperatures.

FREDERICK PYNE LENARD. GEOFFREY WILLIAM METHVEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,862,301 Drexler June 7, 1932 1,994,050 Satow Mar. 12, 1935 2,141,313 Osgood et al Dec. 27, 1938 2,262,770 Lapiana Nov. 18, 1941 2,285,053 Rojas June 2, 1942 2,320,764 Ullrich June 1, 1943 2,337,656 Haycock Dec. 28, 1943 2,381,460 Meyer Aug. 7, 1945 2,403,995 Peters July 16', 1946 2,443,197 Rhodes June 15, 1948 2,444,314 Ruggueri June 29, 1948 2,568,463 Reynolds Sept. 18, 1951 

1. A METHOD OF PRODUCING MULTI-PLY METAL-FOILCARDBOARD MATERIAL COMPRISING FIRST FORMING A COMPOSITE WEB OF CARDBOARD PERMEABLE BY FORMALDEHYDE AND AN IMPERMEABLE METAL FOIL BY ADHESIVELY JOINING THE TWO IN FACE-TO-FACE RELATIONSHIP BY MEANS OF A LIQUID SOLUBLE ADHESIVE WHICH IS CONVERTIBLE TO A WATER INSOLUBLE COMPLEX BY TREATMENT WITH FORMALDEHYDE, THEN APPLYING PRECONDENSED FORMALDEHYDE RESIN ADHESIVE CONTAINING UNCONDENSED FORMALDEHYDE TO THE THEN EXPOSED FACE OF THE CARDBOARD, AND THEN SUBJECTING THE COMPOSITE WEB TO TEMPERATURE CONDITIONS FOR A DURATION OF TIME DEPENDENT UPON SUCH TEMPERATURE; THE TIME BEING OF RELATIVELY LONG DURATION IN THE PRESENCE OF RELATIVELY LOW TEMPERATURES SUCH AS ROOM TEMPERATURES AND OF RELATIVELY SHORTER DURATION IN THE PRESENCE OF RELATIVELY HIGHER TEMPERATURES. 